1. Field of the Invention
The present invention relates to a semiconductor image pickup device such as a complementary metal oxide semiconductor (CMOS) image sensor, a charge coupled device (CCD) or a semiconductor device including the CMOS image sensor or CCD.
2. Description of Related Art
FIG. 7 is a block diagram showing the configuration of a conventional CMOS image sensor representing a conventional semiconductor image pickup device.
In FIG. 7, 1 indicates a conventional CMOS image sensor. 2 indicates each of a plurality of pixel cells for respectively converting an optical signal into an electric signal indicating pixel data. 3 indicates a pixel array which is composed of the pixel cells 2 arranged in a two-dimensional array on a chip surface of the CMOS image sensor 1. The optical signals sent from an object, of which an image is picked up, are received in the pixel array 3 and are convened into the electric signals.
4 indicates a logic input/output terminal for receiving an operation clock signal and data from the outside of the chip and outputting a data output start signal and the like to the outside of the chip. 5 indicates a data set unit for controlling the CMOS image sensor 31 according to the data received in the logic input/output terminal 4. 6 indicates a set point register block for registering the data received in the logic input/output terminal 4, producing a set point for each of a plurality of function circuit blocks according to the data and supplying the set point each function circuit block. 7 indicates a row scanner for selecting a series of pixel cells 2 placed on an arbitrary row of the pixel array 3. 8 indicates a column scanner for selecting a series of pixel cells 2 placed on an arbitrary column of the pixel array 3.
10 indicates a color tone correcting circuit for correcting a color tone (a red component, a green component and a blue component) of the electric signals converted in the pixel array 3 according to the set point sent from the set point register block 6. 11 indicates a gain circuit for correcting the electric signals output from the color tone correcting circuit 10 at a gain (a ratio of the level of each output electric signal to the level of the input electric signal) corresponding to the set point sent from the set point register block 6. 12 indicates a gamma correcting circuit for correcting the electric signals output from the gain circuit 11 to a degree corresponding to the set point sent from the set point register block 6 so as to fit the sensibility of the pixel array 3 to the sensibility of the naked eye. 13 indicates a digital-to-analog (D/A) converter for performing the D/A conversion by using the set point sent from the set point register block 6 and producing a reference voltage Vref. 13a indicates an adder, arranged in the gamma correcting circuit 12, for adding the reference voltage Vref produced in the D/A converter 13 to each electric signal to change the level of the electric signal to a level suitable for a circuit connected to the chip of the CMOS image sensor 1. A group of function circuit blocks 9 is composed of the color tone correcting circuit 10, the gain circuit 11, the gamma correcting circuit 12 with the adder 13a and the D/A converter 13.
14 indicates an analog-to-digital (A/D) converter for performing the A/D conversion for each electric signal corrected in the gamma correcting circuit 12. 15 indicates an output terminal through which each electric signal obtained in the A/D converter 14 is output. 16 indicates an analog pixel output terminal through which each electric signal obtained in the gamma correcting circuit 12 is output.
Next, an operation of the conventional CMOS image sensor 1 will be described below.
In the check of the function of the conventional CMOS image sensor 1, circuit characteristics of the group of function circuit blocks 9 are checked. In this check, many set points ranging from several set points to tens of set points are sent one after another from the set point register block 6 to the group of function circuit blocks 9. Therefore, many gains ranging from one-fold gain to several-fold gain or tens-fold gain are, for example, set in the gain circuit 11.
In a check process of circuit characteristics of a desired function circuit block, data indicating a known set point is sent from the outside of the chip of the conventional CMOS image sensor 1 to the data set unit 5 through the logic input/output terminal 4, the data is registered in the set point register block 6, and the known set point is sent from the set point register block 6 to the desired function circuit block. In this case, a prescribed set point has been already sent to each of the function circuit blocks 9 other than the desired function circuit block. Thereafter, a plurality of optical signals input from the image pickup object to the pixel cells 2 of the pixel array 3 are converted into a plurality of electric signals, the electric signals are corrected in the group of function circuit blocks 9 such as the color tone correcting circuit 10, the gain circuit 11, the gamma correcting circuit 12 with the adder 13a and the D/A converter 13 according to the known set point and the prescribed set points to produce a plurality of corrected analog electric signals, the corrected analog electric signals are converted in the A/D converter 14 into a plurality of corrected digital electric signals, and the corrected digital electric signals are output to the outside of the chip of the conventional CMOS image sensor 1 through the output terminal 15. Also, the corrected analog electric signals are output to the outside of the chip of the conventional CMOS image sensor 1 through the analog pixel output terminal 16.
Thereafter, circuit characteristics of the desired function circuit block are checked according to the optical signals input to the pixel array 3, the corrected analog or digital electric signals and the known set point supplied to the desired function circuit block in the outside of the chip of the conventional CMOS image sensor 1. Therefore, in cases where a plurality of known set points different from each other are sent to the desired function circuit block, circuit characteristics of the desired function circuit block can be precisely checked.
FIG. 8 is an explanatory view of a check sequence of circuit characteristics of a desired function circuit block performed in the conventional CMOS image sensor 1.
As shown in FIG. 8, a first set point is set in the data set unit 5 and is sent to a desired function circuit block in a data set unit setting time period T1. In this case, a prescribed set point has been already sent to each of the function circuit blocks 9 other than the desired function circuit block. Thereafter, when electric signals are prepared in the pixel array 3 during an accumulating time period (or a standby time period) T2, the data outputting is started in the pixel array 3. In detail, in a data outputting time period (or an image pickup time period, for example, corresponding to one frame) T3, all the electric signals are sent from the pixel cells 2 of the pixel array 3 to the group of function circuit blocks 9, and corrected electric signals are output from the group of function circuit blocks 9 to the outside of the conventional CMOS image sensor 1. For example, one electric signal D is acquired in the group of function circuit blocks 9 and is output to the outside in a part of the data outputting time period T3. Thereafter, in a calculating and judging time period T4, the calculation for the electric signals and the judgment (or check) of circuit characteristics of the desired function circuit block are performed in the outside of the conventional CMOS image sensor 1.
Therefore, in this check sequence, in cases where circuit characteristics of the desired function circuit block are checked by sending M set points (first set point, second set point,--, and M-th set point) different from each other to the desired function circuit block one after another, it is required that a series of time periods T1 to T4 is repeated M times.
Because the conventional CMOS image sensor 1 representing the conventional semiconductor image pickup device has the above-described configuration, a problem has arisen that a series of time periods T1 to T4 is required for each set point to check circuit characteristics of the desired function circuit block according to many set points.
Also, a problem has arisen that it takes a lot of time to check circuit characteristics of the group of function circuit blocks 9 in the conventional CMOS image sensor 1.
An object of the present invention is to provide, with due consideration to the drawbacks of the conventional semiconductor image pickup device, a semiconductor image pickup device in which a series of time periods required to check circuit characteristics of a function circuit block or a plurality of function circuit blocks is shortened.
The object is achieved by the provision of a semiconductor image pickup device comprising a pixel array for converting an optical signal of an image input into an electric signal to pickup the image, an automatic set point changing block for producing a plurality of set points different from each other according to data input from an outside in an image pickup time period of the pixel array, and a function circuit block for correcting the electric signal obtained in the pixel array according to each of the set points produced in the automatic set point changing block in the image pickup time period of the pixel array and outputting the corrected electric signals corresponding to the set points to the outside.
In the above configuration, circuit characteristics of the function circuit block are checked in the outside of the semiconductor image pickup device according to the optical signal input to the pixel array, the corrected electric signals output from the function circuit block and the set points produced in the automatic set point changing block. Accordingly, because the set points different from each other are produced in the automatic set point changing block in the image pickup time period of the pixel array, the corrected electric signals corresponding to the plurality of set points can be output by preparing the electric signal only once, and a series of time periods required to check circuit characteristics of the function circuit block can be shortened.
It is preferred that the automatic set point changing block comprises an increment function register for producing the set points by incrementing a set point by a prescribed value in the image pickup time period of the pixel array. Therefore, a current set point obtained by adding the prescribed value to a preceding set point can be repeatedly sent to the function circuit block.
It is preferred that the automatic set point changing block comprises a decrement function register for producing the set points by decrementing a set point by a prescribed value in the image pickup time period of the pixel array. Therefore, a current set point obtained by subtracting the prescribed value from a preceding set point can be repeatedly sent to the function circuit block.
Also, it is preferred that the automatic set point changing block comprises a shift function register for producing the set points by repeatedly doubling or halving a set point in the image pickup time period of the pixel array. Therefore, a current set point obtained by doubling or halving a preceding set point can be repeatedly sent to the function circuit block.
Also, it is preferred that the automatic set point changing block comprises a plurality of set point registers for registering the set points so as to be read out in the image pickup time period of the pixel array. Therefore, a plurality of arbitrary set points different from each other can be sent to the function circuit block.
Also, it is preferred that the automatic set point changing block comprises a memory for storing the set points so as to be read out in the image pickup time period of the pixel array. Therefore, a plurality of arbitrary set points different from each other can be sent to the function circuit block.
The object is also achieved by the provision of a semiconductor image pickup device comprising a pixel array for converting an optical signal of an image input into an electric signal to pickup the image, a plurality of automatic set point changing blocks for respectively producing a plurality of set points different from each other according to data input from an outside in an image pickup time period of the pixel array, and a plurality of function circuit blocks, corresponding to the automatic set point changing blocks respectively, for respectively receiving each of the set points from the corresponding automatic set point changing block at a timing different from those in the other function circuit blocks, respectively correcting the electric signal obtained in the pixel array according to each of the set points at the corresponding timing in the image pickup time period of the pixel array, and outputting the corrected electric signals corresponding to the set points to the outside.
In the above configuration, the timing of the correction of the electric signal in one function circuit block based on each set point differs from those in the function circuit blocks, and circuit characteristics of the function circuit blocks are checked in the outside of the semiconductor image pickup device according to the optical signal input to the pixel array, the corrected electric signals output from the function circuit blocks and the set points produced in the automatic set point changing block. Accordingly, because the set points different from each other are produced in each automatic set point changing block in the image pickup time period of the pixel array, the corrected electric signals corresponding to the plurality of set points produced in the automatic set point changing blocks can be output by preparing the electric signal only once, circuit characteristics of the function circuit blocks can be minutely checked, and a series of time periods required to check circuit characteristics of the function circuit blocks can be shortened.
It is preferred that each automatic set point changing block comprises an increment function register for producing the set points by incrementing a set point by a prescribed value in the image pickup time period of the pixel array. Therefore, a current set point obtained by adding the prescribed value to a preceding set point can be repeatedly sent to each function circuit block.
Also, it is preferred that each automatic set point changing block comprises a decrement function register for producing the set points by decrementing a set point by a prescribed value in the image pickup time period of the pixel array. Therefore, a current set point obtained by subtracting the prescribed value from a preceding set point can be repeatedly sent to each function circuit block.
Also, it is preferred that each automatic set point changing block comprises a shift function register for producing the set points by repeatedly doubling or halving a set point in the image pickup time period of the pixel array. Therefore, a current set point obtained by doubling or halving a preceding set point can be repeatedly sent to each function circuit block.
Also, it is preferred that each automatic set point changing block comprises a plurality of set point registers for registering the set points so as to be read out in the image pickup time period of the pixel array. Therefore, a plurality of arbitrary set points different from each other can be sent to each function circuit block.
Also, it is preferred that each automatic set point changing block comprises a memory for storing the set points so as to be read out in the image pickup time period of the pixel array. Therefore, a plurality of arbitrary set points different from each other can be sent to each function circuit block.
It is preferred that each automatic set point changing block comprises an automatic setting unit which produces the set points optimum to check the corresponding function circuit block. Therefore, the configuration of each automatic set point changing block can be simplified, and an area of a chip of the semiconductor image pickup device can be reduced.